1. Field of the Invention
This invention relates generally to improvements in a bearing supporting arrangement in which rolling bearings are maintained in a floating state relative to a bearing housing under the action of so-called oil film dampers and, more particularly, to a dimensional configuration of elements constituting the bearing supporting arrangement to prevent a bearings from receiving strong reaction from the bearing housing.
2. Description of the Prior Art
A variety of bearing supporting arrangements have been proposed and put into practical use. Of these, one of the type wherein bearings are supported in a floating state to a bearing housing has been disclosed, for example, in Japanese Utility Model Provisional Publication No. 61-134536. In this conventional arrangement, the bearings are adapted to rotatably support a turbine shaft of an exhaust gas turbocharger. The bearings are fixedly provided on their outer periphery respectively with oil film damper members which are supported through oil films to the inner periphery of the bearing housing, constituting so-called oil film dampers. The bearing housing is provided at its inner periphery with a pair of stop rings to which the oil film damper members are respectively contactable upon a thrust being applied through the turbine shaft to the oil film damper members. In other words, positioning of the turbine shaft in a thrust direction is accomplished by these stop rings.
However, difficulties have been encountered in the above conventional arrangement, in which it is very difficult to obtain a high accuracy of positioning for the turbine shaft relative to the bearing housing by using the stop rings because grooves (for the stop rings) formed in the bearing housing unavoidably have a relatively large clearance to facilitate installation operation of the stop rings.
In order to overcome the above problems, some propositions may be made; however, other problems will arise in which the oil film damper members are brought into contact with the inner peripheral surface of the bearing housing when a thrust is applied to the turbine shaft, and therefore the outer race of the bearing receives a reaction from the inner periphery of the bearing housing, thereby causing a misalignment between the inner and outer races of the bearing. This misalignment deteriorates smooth rotation of the bearing, degrading the durability of the bearing.